Stem borers

Caused by: Scirpophaga incertulas
Problem Category: Insect
Symptoms: Longitudinal white patches on leaf sheaths; central leaf whorl drying out and turning brown; tillers drying out without producing panicles; panicles may dry out or may produce no grain; adult Insect are nocturnal moths which lay their eggs on the leaves or leaf sheaths of the rice plants; larvae are legless grubs which feed on leaf sheaths before entering the stem of the pant
Comments: Stem borers are generally considered to be the most damaging Insect of rice
Management: Stem borers are difficult to control with insecticides as once they bore inside the stem they are protected from chemical sprays; in order for chemical control to be successful, repeated applications of appropriate insecticide must be made to the foliage; granular formulations give better control than sprays; clipping seedling prior to transplanting can successfully reduce moth numbers as eggs are laid at leaf tips; harvesting plants at ground level can remove the majority of larvae from the field; plowing or flooding the remaining stubble will kill off most of the remainder of the larvae in the field
Control: keep Trichogramma chilonis cards in the field and spray sithphal oil 2ml/litre water is recommended to control stem borer